Various types of disposable absorbent articles such as disposable diapers, training pants, swim pants, incontinence articles, and the like, utilize a chassis incorporating an absorbent system and an elastomeric waistband. The waistband provides for enhanced fit, comfort to the wearer, and improved product performance.
Much attention has been paid in the art to development of various elastomeric waistband configurations. For example, U.S. Pat. No. 4,205,679 discloses various embodiments of a pull-on pant-like article having gathered elastic waistband portions. U.S. Pat. No. 4,639,949 describes a disposable absorbent garment having an improved elastic waistband with an elastic element joined in a stretched condition to a marginal portion of an exterior panel of the garment with a plurality of spaced bond points. U.S. Pat. No. 4,904,251 describes a disposable diaper having gathered elasticized front and back waistband portions. Tape fasteners are provided on back side flaps for fastening the front and back regions of the article together on a wearer. U.S. Pat. No. 5,676,661 similarly discloses a diaper configuration having elasticized waistband portions and tape members extending from the side margins of the back waist region. The tape members include a fastening strip, such as a hook-type material, that attaches to a corresponding landing pad, material provided on the front waist region to secure the article to a wearer.
With a known commercial disposable diaper (the HUGGIES® brand from Kimberly-Clark Corp. of Neenah, Wis., USA) elasticity is provided to the back waistband portion by elastomeric strips bonded to side edges of the chassis at the waist region. A non-elastic material strip is bonded to the outboard end of the elastomeric strips, and a micro-hook material strip is laminated to this non-elastic material. For securing the diaper on a wearer, the hook material attaches to a piece of non-woven web material adhered to the outer cover at the front waist region. Thus, with this configuration, the chassis has generally non-elastomeric waistband portions, and the desired degree of elasticity is provided around the waist of a wearer by the elastomeric tab strips.
With a typical absorbent article configuration, the circumference of the waist area in a relaxed state is significantly smaller than the waist of an intended wearer in the designed size range of the article. The waist area of the article must thus expand or stretch a significant degree. With many typical absorbent article constructions, the ratio of elastomeric materials to non-elastomeric materials in the waist region when the article is fully retracted is such that the elastomeric materials make up about 5% to about 25% of the entire circumference of the retracted waist area. However, the elastomeric regions are highly retracted and extend (stretch) between about 50% to about 120% of their retracted length on the average target wearer. This results in a relatively high tension being placed on the elastomeric materials in use of the article. With such high tension, stress relaxation of the elastomeric materials becomes a concern. Additionally, waistbands with an excessively high tension of the elastic elements result in an uncomfortable fit, red-marking, and/or difficulty in pulling a pant-like structure up or down.
To ensure that article performance is not degraded over time due to stress relaxation of the elastomeric materials, it is often the case that relatively expensive elastomeric polymers are required that are designed to function with minimal stress relaxation. These elastomeric materials account for a significant portion of the overall cost of the article.
The present invention provides an improved elastic waistband configuration that may help alleviate deficiencies of current configurations.